Web applications have been used in various fields including business applications. Further, with the technical progress of business applications with rich client technology using script codes, there remains a need for the convenience of simple execution of web applications when a web browser is installed in a client device. According to the utilization of the web applications, it is required that the web applications achieve high availability, fast response speed, and usability. In particular, since the performance of a web application is affected by the response speed, research has been conducted to improve the response speed.
One field of research is directed to a method that has been widely used and has a superior effect, a high speeding method using a cache is exemplified. A cache in a web system that is an execution basis of a web application is a mechanism that temporarily stores a web page loaded by a web browser on a network such as a web server or a proxy server. With respect to a request to a web page, the cache returns the response instead of a web server generating a response and returning the response. The cache is generally provided between a client device and a server device. When the response is returned from the cache, communication time and time for generating the response can be shortened and the response speed can be improved.
A method of determining whether a cache can be used is different according to a type of a web application or a web page. However, in order to determine whether the cache can be used, it is needed to detect whether the cache hit is made for every access to a web page. As a method of detecting a cache hit, a method of determining the case where a time stamp of a web page is inquired to the server device and the corresponding time stamp is compared with a time stamp of the read web page and updated as a cache hit (refer to JP-A-Hei15 (2003)-85082), and a method in which image data where a cache is not hit is inserted into a web page and a server device determines when access is given to only the image data on the basis of an access history to the web page and the image data as cache hit (refer to JP-T-2004-507816) are known.